1. Field of the Invention
The invention relates generally to semiconductor manufacturing. More particularly, the invention pertains to an improved method of fabricating multimedia cards (MMC).
2. State of the Art
One type of electronic assembly containing semiconductor components is generally referred to as “card”. Examples of such “cards” include multimedia cards (MMC) such as used in digital cameras and the like, memory cards, smart cards and personal computer memory card international association (PCMCIA) cards. In the industry, these types of cards are sometimes referred to collectively as “semiconductor cards,” “multimedia cards” or “daughter boards.”
One of the conventional methods of making multimedia cards (MMC) takes an assembled circuit board and places a protective cover sheet over the top surface of the printed PCB. A plastic top cover is positioned over the protective cover sheet and a plastic bottom plate member is positioned beneath the PCB member. The four stacked members are assembled together as a completed multimedia card. The advantages to this process is that the assembly process is simple, no special technique is required and the assembled PCB can be salvaged. One disadvantage to this process is that there is a requirement for separate top and bottom plastic case members. The thickness of the top and bottom case members is limited due to the overall height limitation for the multimedia cards. An additional disadvantage is that there is no sealing of the components on the printed circuit board and moisture may cause component failure.
A second conventional method for assembling a multimedia card requires five separate components. These components are stacked from top to bottom include a metal sheet cover, a first thermo-bond film, a plastic frame, a second thermo-bond film and an assembled PCB. The most important advantage to this process is that it involves a straight forward design. The advantages of the process is that the process is complicated, the bonding process is difficult to control and there is a high cost due to the number of components and processes. Also there is no sealing of the components and moisture may cause component failure. Lastly it is difficult to salvage the PCB. In the process just described, a central plastic frame provides structure for spacing the top metal sheet from the top surface of the PCB and prevents the PCB from being crushed during assembly.
It is an object of the invention to provide an improved method for manufacturing multimedia cards such as memory cards.
It is also an object of the invention to produce multimedia cards having superior construction.
It is another object of the invention to provide improved multimedia cards having a rugged construction in which all of the electrical components on the top surface of the PCB are all sealed and protected from dust, water, weather and are shock proof.
It is also an object of the invention to provide a more economical method for manufacturing multimedia cards.
It is an additional object of the invention to provide an improved method for manufacturing multimedia cards which allows damage to the PCB to be minimized.